The invention relates to a method and apparatus for processing foodstuffs; more particularly, this invention relates to methods and apparatus for processing rice to achieve a quick-cooking rice.
Mankind is continually searching for new and better methods of cooking cereal grains, vegetables and other foodstuffs. In large scale commercial operations, the cooking of foodstuffs requires special apparatus and specially adapted cooking methods that will provide a uniform and desirable food product while at the same time handling large quantities of foods.
In the cooking of certain starch-containing foods such as vegetables and cereal grains, several problems are encountered. First, the food granules must be moved from storage tanks to processing vessels, and in some cases to holding tanks or cooking vessels, and then they may be distributed to dryers to remove water from the food granules. The physical transport of the food granules during such processing must be well regulated and maintained to achieve a desirable flow of food particles through the processing system from one processing step to another, without undesirable clumping or aggregation of food granules.
In certain cases the physical handling and heat applied to grains during cooking is designed to result in physical or chemical changes to the starch or other molecules that are contained -in the food stock itself. For example, in the cooking of cereal grains, such as rice, the goal is to gelatinize the starches in the grain. In such a process, loose starch molecules may be leached out of the food granules or the starch molecules may be ruptured as a result of handling or processing. If that occurs, then cooking processes may tend to glue together the granules, slowing advancement of the food product through the processing system. This "gluing" problem is particularly troublesome in the cooking of rice and, if allowed to proceed unabated, will cause the surface of rice particles to stick together, causing large globules to form, making further transport and processing of the rice impractical, if not impossible.
In the past, the problem of "gluing" of food granules by the release or rupture of starch molecules could be controlled, at least to a limited degree, by using large amounts of fluid in transporting the food through the processing machinery, cookers, conduits, and the like. Typically, water is used as a transport fluid, and large amounts of water tend to dilute the "glue" (free hydrated starch), thereby minimizing the adverse effect of free starch. By using large amounts of water, cereal grains may be processed without the undesirable globules forming to slow the transport of the grains through processing equipment. However, such use of water to dilute this gluing effect results in spent process water with large amounts of free starch which must be discarded or further processed such as by water treatment.
Unfortunately, many communities have greatly increased the fees that commercial users must pay for water in such food processing operations. As such, the processing of food wherein large amounts of water are required has become extremely expensive in these communities, and newer and better methods of transporting and cooking food in a processing system, while using less water, are highly desirable.
Also, in the past, water used in a food processing system for transport of food has been discarded as waste water at the point in the processing after which the water is no longer needed for transport of the food. However, recent environmental regulations have greatly curtailed the amount of waste water and wastes materials that may be disposed of by food processing facility. Moreover, many public utilities and water companies charge corporate water consumers not only on the basis of the amount of water consumed, but also on the basis of the number of gallons of waste water that is discharged back into the public sewer system. Therefore, it is desirable to limit the amount of waste water that is produced by a food processing plant.
Additionally, the greater the amount of water used in commercial processing, the greater is the amount of heat energy that must be applied to reach a desirable temperature level. If less water is utilized in a batch processing system, substantial savings in power consumption can be achieved. A batch processing system may, therefore, operate at a lower cost per pound of food processed.
Commercial rice cooking methods consume and excrete very large amounts of water. For example, in the commercial cooking of one cup of rice, prior methods required as much as a 20:1 ratio of water used to rice produced pursuant to the processing method. A great advantage in food processing would be a cooking method that allows food granules, such as rice, to be cooked with a ratio of water consumption to food production of as little as 2:1 or perhaps even less.
Another problem in the food industry is the production of a uniform final product, especially in high production batch or continuous processes. For example, cooking cereal grains in a uniform manner so that each grain receives substantially identical conditions during cooking presents a challenge.
The challenge arises because numerous variables exist in processing and because of the difficulty in exposing each grain to the same overall history of cooking conditions. The first variable is the amount of heat applied. The greater the amount of heat applied, the greater the gelatinization of starch within the grain, and the quicker the rice will cook. Furthermore, an increase in the pressure during the cooking of rice will increase the rate at which the starch is gelatinized, and therefore, it will speed the cooking of the rice. If the rate of gelatinization of the rice is too high, or if the pressure and temperature conditions are not optimum during the cooking and drying of the rice, the individual grains may be physically harmed by the formation of small pockets of air or dead space within the grain itself. These pockets cause the rice to become brittle after it is dried, resulting in an inferior product that consumers find undesirable.
Accordingly, what has been needed in the industry is a cooking apparatus and method that will provide for the uniform cooking of the food granules in a continuous processing system without using or excreting excess water, and while avoiding the gluing together of the food granules.